A jibboom (also spelt jib-boom) is a spar used to extend the length of a bowsprit on sailing ships. It can itself be extended further by a flying jib-boom. The heel (i.e. rear and lower) end of the flying jib-boom is attached to the jib-boom, and the heel of the jib-boom to the bowsprit. The point (i.e. higher and fore end) of the flying jib-boom is generally the fore-most extent of a ship. The jib- and flying jib- booms carry the tacks of the jib and flying jib sails, respectively, and the stay for the fore topgallant mast and the royal stay.
The jib-boom is — as the name suggests — the boom for the jib, extending its foot. On smaller, merchant, sailing ships, it is commonly attached to the bowsprit by a cap and a saddle, either lashed down or secured with a crupper chain. Alternatively, it can be attached by a boom iron and a cap, or even by two boom irons. The cap and saddle allow it to be withdrawn aft along the bowsprit as a ship enters harbour, reducing the opportunity for passing ships to glance against it and snap it off from the bowsprit.